The present invention relates to a technique of enriching uranium with .sup.235 U isotope, and more particularly, it relates to a method of uranium isotope enrichment by utilizing a photochemically selective effect.
Since uranium enriched with .sup.235 U must be used as a nuclear fuel in a nuclear reactor, it is an important technique to enrich uranium in a nuclear fuel cycle.
The uranium enrichment techniques now in use include centrifuge separation and gaseous diffusion methods, while those under development include a laser method.
The laser method comprises selectively exciting only a lighter isotope component with a laser by taking advantage of a slight difference in absorption spectrum between .sup.235 U and .sup.238 U due to isotope shift. In this method, gasified uranium is irradiated with a laser beam having a high wavelength purity. Further, a molecular laser method has also been developed, wherein gaseous molecules containing uranium (VI) are expanded and cooled with a diffuser or the like and then irradiated with a laser beam to selectively excite only the lighter isotope component.
Although the above-described optical uranium enrichment according to the laser method has an advantage that a separation factor higher than that of other methods can be obtained, this method has problems in that the gasification of uranium makes the handling thereof complicated and that a laser beam having a high wavelength purity must be used as the exciting light source. The molecular laser method is troublesome in that the molecules to be treated must be cooled to a cryogenic temperature.